A device of the type set out above embodied as an driving device for driving in mechanical fastening means, such as, for example, staples, is known from EP 0 191 186 A2. In the known device a device body is fitted with a pressure medium container, which, when actuated by means of a valve system, serves to exert pressure on a piston, which is connected to an impact ram. In the known expulsion device the pressure medium container is in the form of a CO2 cartridge, the filling pressure of which acts on the piston connected to the impact ram when an actuating device is operated, thereby bringing about a forward movement of the impact ram. In order to implement a return movement of the piston, so as to move the impact ram back into its initial position for repeating the expulsion procedure, the piston is returned to its initial position by means of a mechanical carrier device.
As a result of the mechanically brought about return of the piston into the initial position, only relatively low expulsion frequencies are possible with the known expulsion device. Furthermore, returning the piston into the initial position assumes the application of a corresponding manual force. Overall in this way only a relative low stapling output is possible.
The aim of the present invention is therefore to permit an increase in the expulsion frequency with an expulsion device which is fitted with an exchangeable pressure medium container and can therefore be operated independently of the mains.